This invention relates to a vacuum interrupter device in which a non-linear resistor or resistors for suppressing surge caused by make and break of the vacuum interrupter may be placed and removed easily. In order to suppress make-and-break surges of the conventional vacuum interrupter, a CR suppressor composed of a resistance and a capacitor connected in series was usually connected between the load side terminal and the ground. The CR suppressor, however, had a drawback that it could not be contained without extension of the panel of the interrupter device or use of a larger panel because of its large size, thereby requiring a large space.
In order to avoid the above-mentioned drawback, there was considered use of a relatively small non-linear resistor instead of the CR suppressor. Such resistor, e.g., composed of metallic oxide containing zinc oxide (ZnO) as a main component, usually has a high resistance, though, if applied with an overvoltage above the prescribed level, the resistance will be decreased quickly and reduced in performance as a high-resistor to suppress the overvoltage substantially to a prescribed lower level.
Usually a vacuum interrupter device is equipped with at least a pair of terminals, one of which is an upper terminal and the other of which is a lower terminal. For example, when a plurality of devices for use in three-phase circuit are used in a state piled up in an enclosed-type power board, electrical load must be connected to the upper terminals or lower terminals of the device according to the piled position thereof. Therefore, in the vacuum interrupter device, connections of the non-linear resistors with the terminals are required to be easily changed from any one of the upper terminals to a corresponding one of the lower terminals or vice versa. In the prior art, however, there existed no such vacuum interrupter device as may fullfil the above-mentioned requirements satisfactorily.